Light-irradiation heat treatment apparatus

ABSTRACT

A semiconductor wafer held by a holding part in a chamber is irradiated and heated with halogen light emitted from a plurality of halogen lamps. A cylindrical louver and an annular light-shielding member, both made of opaque quartz, are provided between the halogen lamps and the semiconductor wafer. The outer diameter of the light-shielding member is smaller than the inner diameter of the louver. Light emitted from the halogen lamps and passing through a clearance between the inner wall surface of the louver and the outer circumference of the light-shielding member is applied to a peripheral portion of the semiconductor wafer where a temperature drop is likely to occur. On the other hand, light travelling toward an overheat region that has a higher temperature than the other region and appears in the surface of the semiconductor wafer when only a louver is installed is blocked off by the light-shielding member.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application is a divisional of prior U.S. patentapplication Ser. No. 15/049,286, filed Feb. 22, 2016, by Makoto ABE,Hikaru KAWARAZAKI, Hideaki TANIMURA and Masashi FURUKAWA, entitled“LIGHT-IRRADIATION HEAT TREATMENT APPARATUS,” which claims priority toJapanese Patent Application Nos. 2015-044631, filed Mar. 6, 2015,2015-051682, filed Mar. 16, 2015 and 2015-051700, filed Mar. 16, 2015.The contents of each of the patent applications listed above areincorporated in full herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a heat treatment apparatus for heatinga sheet precision electronic substrate (hereinafter, simply referred toas a “substrate”) such as a disk-shaped semiconductor wafer byirradiating the substrate with light.

Description of the Background Art

In the process of manufacturing a semiconductor device, the introductionof impurities is an essential step for forming pn junctions in asemiconductor wafer. At present, it is common to introduce impurities byion implantation and subsequent annealing. Ion implantation is atechnique for physically doping impurities by causing impurity elementssuch as boron (B), arsenic (As), or phosphorus (P) to be ionized andcollide with a semiconductor wafer with a high acceleration voltage. Thedoped impurities are activated by annealing. At this time, if theannealing time becomes about several seconds or longer, the dopedimpurities are deeply diffused by heat, and as a result, the junctiondepth may become too deeper than required and hinder the formation of agood device.

In view of this, flash-lamp annealing (FLA) is recently receivingattention as an annealing technique that allows semiconductor wafers tobe heated in an extremely short time. Flash-lamp annealing is a heattreatment technique using xenon flash lamps (hereinafter, flash lampssimply referred to indicate xenon flash lamps) to irradiate the surfaceof a semiconductor wafer with flash light so that the temperature ofonly the surface of the semiconductor wafer that is doped withimpurities is raised in an extremely short time (several milliseconds orless).

The radiation spectral distribution of xenon flash lamps ranges fromultraviolet to near-infrared regions, with the xenon flash lamps havingshorter wavelengths than conventional halogen lamps, and approximatelycoincides with the fundamental absorption band of silicon semiconductorwafers. Thus, in the case where flash light is applied from xenon flashlamps to a semiconductor wafer, less light will be transmitted throughthe semiconductor wafer and therefore it is possible to quickly raisethe temperature of the semiconductor wafer. It has also been found thatthe temperature of only the vicinity of the surface of the semiconductorwafer will selectively be raised with extremely short-time applicationof flash light for several milliseconds or less. Thus, extremelyshort-time temperature rise with the xenon flash lamps enables theimpurities to be activated simply without being diffused deeply.

As examples of such a heat treatment apparatus using xenon flash lamps,U.S. Pat. No. 4,649,261 and US 2003/0183612 A1 disclose heat treatmentapparatuses that achieve desirable heat treatment with a combination ofpulsed light-emitting lamps such as flash lamps that are arranged on thefront side of a semiconductor wafer and continuous lighting lamps suchas halogen lamps that are arranged on the rear side of the semiconductorwafer. In the heat treatment apparatuses disclosed in U.S. Pat. No.4,649,261 and US 2003/0183612 A1, a semiconductor wafer is preheated toa certain degree of temperature with, for example, halogen lamps, andthen the temperature of the semiconductor wafer is raised to a desiredtreatment temperature by pulse heating with flash lamps.

Preheating with the halogen lamps, as disclosed in U.S. Pat. No.4,649,261 and US 2003/0183612 A1, has a processing advantage that thetemperature of a semiconductor wafer will be raised to a relatively highpreheating temperature in a short time, but at the same time, may causethe temperature of the peripheral portion of the wafer to be lower thanthe temperature of the central portion of the wafer. Conceivable causesof such an uneven temperature distribution include heat radiation fromthe peripheral portion of the semiconductor wafer and heat conductionfrom the peripheral portion of the semiconductor wafer to a relativelylow-temperature quartz susceptor. To solve this problem, Japanese PatentApplication Laid-Open No. 2012-174879 proposes installation of acylindrical louver made of a semitransparent material between halogenlamps and a semiconductor wafer to make uniform the temperaturedistribution in the surface of the wafer during preheating.

Although the installation of the louver as proposed in Japanese PatentApplication Laid-Open No. 2012-174879 certainly ameliorates the problemof a temperature drop in the peripheral portion of the semiconductorwafer, there is still a tendency for the temperature of the peripheralportion of the semiconductor wafer to be lower than the temperature ofthe central portion, and uniformity in the temperature distribution inthe surface has not reached a sufficient level. In addition, it has beennewly found out that the installation of the louver as proposed inJapanese Patent Application Laid-Open No. 2012-174879 may, on thecontrary, increase the temperature of a region that is located slightlyinward of the peripheral portion of the semiconductor wafer.

SUMMARY OF THE INVENTION

The present invention is directed to a heat treatment apparatus forheating a disk-shaped substrate by irradiating the substrate with light.

In one aspect of the present invention, the heat treatment apparatusincludes a chamber that houses a substrate, a holding part that holds asubstrate in the chamber, a light irradiation part in which a pluralityof rod-shaped lamps are arranged in a light source region that isgreater than a major surface of the substrate held by the holding partand that opposes the major surface, a cylindrical louver that isprovided between the light irradiation part and the holding part, with acentral axis of the louver passing through a center of the substrate,and that is impervious to the light emitted from the light irradiationpart, and a light-shielding member that is provided between the lightirradiation part and the holding part and that is impervious to thelight emitted from the light irradiation part.

The heat treatment apparatus that includes the opaque cylindrical louverand the opaque light-shielding member allows part of the lighttravelling from the light irradiation part toward the substrate to beblocked off by the louver and the light-shielding member and therebyallows the temperature distribution in the surface of the substrate tobe uniform.

In another aspect the present invention, the heat treatment apparatusincludes a chamber that houses a substrate, a holding part that holds asubstrate in the chamber, a light irradiation part in which a pluralityof rod-shaped lamps are arranged in a region that is greater than amajor surface of the substrate held by the holding part and that opposesthe major surface, a cylindrical first light-shielding member that isprovided between the light irradiation part and the holding part, with acentral axis of the first light-shielding member passing through acenter of the substrate, and that is impervious to the light emittedfrom the light irradiation part, and a flat-plate annular secondlight-shielding member that is provided between the light irradiationpart and the holding part, with a central axis of the secondlight-shielding member passing through the center of the substrate, andthat is impervious to the light emitted from the light irradiation part,the second light-shielding member having outer dimensions smaller thaninner dimensions of the first light-shielding member.

The heat treatment apparatus that includes the opaque cylindrical firstlight-shielding member and the opaque flat-plate annular secondlight-shielding member, with the outer dimensions of the secondlight-shielding member being smaller than the inner dimensions of thefirst light-shielding member, allows part of the light travelling fromthe light irradiation part toward the substrate to be blocked off by thefirst light-shielding member and the second light-shielding member andthereby allows the temperature distribution in the surface of thesubstrate to be uniform.

In another aspect of the present invention, the heat treatment apparatusincludes a chamber that houses a substrate, a holding part that holds asubstrate in the chamber, a light irradiation part in which a pluralityof rod-shaped lamps are arranged in a region that is greater than amajor surface of the substrate held by the holding part and that opposesthe major surface, a cylindrical first louver that is provided betweenthe light irradiation part and the holding part, with a central axis ofthe first louver passing through a center of the substrate, and that isimpervious to the light emitted from the light irradiation part, and acylindrical second louver that is provided between the light irradiationpart and the holding part, with a central axis of the second louverpassing through the center of the substrate, and that is impervious tothe light emitted from the light irradiation part. The first louver andthe second louver have the same height, the first louver has an innerdiameter greater than an outer diameter of the second louver, and thesecond louver is located inward of the first louver.

Since the opaque cylindrical second louver is located inward of theopaque cylindrical first louver, a cylindrical clearance is createdbetween the first louver and the second louver. This configurationincreases directivity of the light emitted from the light irradiationpart and entering the clearance and thereby allows the temperaturedistribution in the surface of the substrate to be uniform.

Preferably, the first louver and the second louver are located with aclearance between an inner wall surface of the first louver and an outerwall surface of the second louver, the clearance opposing a peripheralportion of the substrate.

This configuration increases directivity of the light travelling towardthe peripheral portion of the substrate where a temperature drop islikely to occur, and thereby allows the temperature distribution in thesurface of the substrate to be uniform.

In another aspect of the present invention, the heat treatment apparatusincludes a chamber that houses a substrate, a holding part that holds asubstrate in the chamber, a light irradiation part in which a pluralityof rod-shaped lamps are arranged in a region that is greater than amajor surface of the substrate held by the holding part and that opposesthe major surface, and a plurality of cylindrical louvers that arelocated between the light irradiation part and the holding part, withcentral axes of the louvers passing through a center of the substrate,and that is impervious to the light emitted from the light irradiationpart, the plurality of louvers having the same height and beingsequentially arranged from outside to inside in descending order ofouter diameters of the plurality of louvers. Since the plurality ofopaque cylindrical louvers are sequentially located from outside toinside in descending order of their outer diameters, cylindricalclearances are created between the louvers. This configuration increasesdirectivity of the light emitted from the light irradiation part andentering the clearances and thereby allows the temperature distributionin the surface of the substrate to be uniform.

Thus, it is an object of the present invention to make uniform thetemperature distribution in the surface of a substrate.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a configuration of aheat treatment apparatus according to the present invention;

FIG. 2 is a perspective view illustrating the entire external appearanceof a holding part;

FIG. 3 is a plan view of the holding part as viewed from above;

FIG. 4 is a side view of the holding part as viewed from one side;

FIG. 5 is a plan view of a transfer mechanism;

FIG. 6 is a side view of the transfer mechanism;

FIG. 7 is a plan view illustrating the layout of a plurality of halogenlamps;

FIG. 8 is a perspective view of a louver;

FIG. 9 is a perspective view illustrating the entire externalappearances of the louver and a light-shielding member according to thefirst preferred embodiment;

FIG. 10 illustrates how the optical path is controlled by the louver andthe light-shielding member;

FIG. 11 is a plan view of a light-shielding member according to a secondpreferred embodiment;

FIG. 12 is a plan view of a light-shielding member according to a thirdpreferred embodiment;

FIG. 13 is a plan view of a light-shielding member according to a fourthpreferred embodiment;

FIG. 14 illustrates the temperature distribution in the surface of asemiconductor wafer in the case where only the louver is installed;

FIG. 15 illustrates the layout of a louver and a light-shielding memberaccording to a fifth preferred embodiment;

FIG. 16 illustrates the layout of a louver and a light-shielding memberaccording to a sixth preferred embodiment;

FIG. 17 illustrates the layout of a louver and a light-shielding memberaccording to a seventh preferred embodiment;

FIG. 18 is a longitudinal cross-sectional view of a configuration of aheat treatment apparatus according to an eighth preferred embodiment;

FIG. 19 is a perspective view of an outer louver and an inner louver;and

FIG. 20 illustrates how the optical path is controlled by the outerlouver and the inner louver.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the drawings.

First Preferred Embodiment

FIG. 1 is a longitudinal cross-sectional view of a configuration of aheat treatment apparatus 1 according to the present invention. The heattreatment apparatus 1 of the present preferred embodiment is aflash-lamp annealing apparatus for heating a disk-shaped semiconductorwafer W having a diameter of 300 mm as a substrate by irradiating thesemiconductor wafer W with flash light. The semiconductor wafer W isdoped with impurities before being transported into the heat treatmentapparatus 1, and the doped impurities are activated through heattreatment by the heat treatment apparatus 1. For easy understanding ofdrawings, the dimensions and number of each constituent element may beexaggerated or simplified as necessary in FIG. 1 and subsequentdrawings.

The heat treatment apparatus 1 includes a chamber 6 that houses thesemiconductor wafer W, a flash heating part 5 with a plurality ofbuilt-in flash lamps FL, and a halogen heating part 4 with a pluralityof built-in halogen lamps HL. The flash heating part 5 is located abovethe chamber 6, and the halogen heating part 4 is located below thechamber 6. Also, a louver 21 and a light-shielding member 25 are locatedbetween the halogen heating part 4 and the chamber 6. The heat treatmentapparatus 1 further includes, within the chamber 6, a holding part 7that holds the semiconductor wafer W in a horizontal position and atransfer mechanism 10 for transferring the semiconductor wafer W betweenthe holding part 7 and the outside of the heat treatment apparatus 1.The heat treatment apparatus 1 further includes a controller 3 thatcontrols operating mechanisms located in the halogen heating part 4, theflash heating part 5, and the chamber 6 for heat treatment of thesemiconductor wafer W.

The chamber 6 is configured by mounting quartz chamber windows on thetop and bottom of a tubular chamber side portion 61. The chamber sideportion 61 has a generally tubular shape with upper and lower openings,the upper opening being equipped with and closed by an upper chamberwindow 63, and the lower opening being equipped with and closed by alower chamber window 64. The upper chamber window 63, which forms theceiling of the chamber 6, is a disk-shaped member made of quartz andfunctions as a quartz window that allows the flash light emitted fromthe flash heating part 5 to be transmitted into the chamber 6. The lowerchamber window 64, which forms the floor of the chamber 6, is also adisk-shaped member made of quartz and functions as a quartz window thatallows the light emitted from the halogen heating part 4 to betransmitted into the chamber 6.

Also, a reflection ring 68 is mounted on the upper portion of the innerwall surface of the chamber side portion 61, and a reflection ring 69 ismounted on the lower portion thereof. The reflection rings 68 and 69both have an annular shape. The upper reflection ring 68 is mounted bybeing fitted into the chamber side portion 61 from above. On the otherhand, the lower reflection ring 69 is mounted by being fitted into thechamber side portion 61 from below and fastened with screws (not shown).That is, the reflection rings 68 and 69 are both removably mounted onthe chamber side portion 61. The inner space of the chamber 6, i.e., thespace surrounded by the upper chamber window 63, the lower chamberwindow 64, the chamber side portion 61, and the reflection rings 68 and69, is defined as a heat treatment space 65.

The reflection rings 68 and 69 mounted on the chamber side portion 61form a recessed portion 62 in the inner wall surface of the chamber 6.That is, the recessed portion 62 is surrounded by the central portion ofthe inner wall surface of the chamber side portion 61 on which thereflection rings 68 and 69 are not mounted, the lower end surface of thereflection ring 68, and the upper end surface of the reflection ring 69.The recessed portion 62 is horizontally formed in an annular shape inthe inner wall surface of the chamber 6 and surrounds the holding part 7that holds the semiconductor wafer W.

The chamber side portion 61 and the reflection rings 68 and 69 are madeof a metal material (e.g., stainless steel) having excellent strengthand excellent heat resistance. The inner circumferential surfaces of thereflection rings 68 and 69 are mirror-finished by electrolytic nickelplating.

The chamber side portion 61 has a transport opening (throat) 66 throughwhich the semiconductor wafer W is transported into and out of thechamber 6. The transport opening 66 is openable and closable with a gatevalve 185. The transport opening 66 is communicatively connected to theouter circumferential surface of the recessed portion 62. When opened bythe gate valve 185, the transport opening 66 allows the semiconductorwafer W to be transported into and out of the heat treatment space 65from the transport opening 66 through the recessed portion 62. When thetransport opening 66 is closed by the gate valve 185, the heat treatmentspace 65 in the chamber 6 becomes an enclosed space.

The upper portion of the inner wall of the chamber 6 has a gas supplyport 81 through which a treatment gas (in the present preferredembodiment, a nitrogen gas (N₂)) is supplied into the heat treatmentspace 65. The gas supply port 81 is located at a position above therecessed portion 62 and may be located in the reflection ring 68. Thegas supply port 81 is communicatively connected to a gas supply pipe 83via a buffer space 82 that is formed in an annular shape inside the sidewall of the chamber 6. The gas supply pipe 83 is connected to anitrogen-gas supply source 85. Also, a valve 84 is interposed in thepath of the gas supply pipe 83. When the valve 84 is open, a nitrogengas is supplied from the gas supply source 85 into the buffer space 82.The nitrogen gas flowing into the buffer space 82 flows throughout thebuffer space 82 that has lower fluid resistance than the gas supply port81, and is supplied through the gas supply port 81 into the heattreatment space 65.

On the other hand, the lower portion of the inner wall of the chamber 6has a gas exhaust port 86 through which the gas in the heat treatmentspace 65 is exhausted. The gas exhaust port 86 is located at a positionbelow the recessed portion 62 and may be located in the reflection ring69. The gas exhaust port 86 is communicatively connected to a gasexhaust pipe 88 via a buffer space 87 that is formed in an annular shapeinside the side wall of the chamber 6. The gas exhaust pipe 88 isconnected to an exhaust part 190. Also, a valve 89 is interposed in thepath of the gas exhaust pipe 88. When the valve 89 is open, the gas inthe heat treatment space 65 is exhausted from the gas exhaust port 86through the buffer space 87 into the gas exhaust pipe 88. Aconfiguration is also possible in which a plurality of gas supply ports81 and a plurality of gas exhaust ports 86 are provided in thecircumferential direction of the chamber 6, or a configuration ispossible in which the gas supply port 81 and the gas exhaust port 86 areslit-shaped. The gas supply source 85 and the exhaust part 190 may bemechanisms provided in the heat treatment apparatus 1, or may beutilities in a factory where the heat treatment apparatus 1 isinstalled.

One end of the transport opening 66 is also connected to a gas exhaustpipe 191 through which the gas in the heat treatment space 65 isexhausted. The gas exhaust pipe 191 is connected via a valve 192 to theexhaust part 190. When the valve 192 is open, the gas in the chamber 6is exhausted through the transport opening 66.

FIG. 2 is a perspective view illustrating the entire external appearanceof the holding part 7. FIG. 3 is a plan view of the holding part 7 asviewed from above, and FIG. 4 is a side view of the holding part 7 asviewed from one side. The holding part 7 includes a base ring 71,connecting parts 72, and a susceptor 74. The base ring 71, theconnecting parts 72, and the susceptor 74 are all made of quartz. Thatis, the entire holding part 7 is made of quartz.

The base ring 71 is an annular quartz member. The base ring 71 is placedon the bottom surface of the recessed portion 62 and supported by thewall surface of the chamber 6 (see FIG. 1). On the upper surface of thebase ring 71 having an annular shape, a plurality of (in the presentpreferred embodiment, four) connecting parts 72 are provided upright inthe circumferential direction of the base ring 71. The connecting parts72 are also quartz members and fixedly attached to the base ring 71 bywelding. Note that the base ring 71 may have an arc shape that is anannular shape with a missing part.

The flat plate-like susceptor 74 is supported by the four connectingparts 72 provided on the base ring 71. The susceptor 74 is a generallycircular flat plate-like member made of quartz. The diameter of thesusceptor 74 is greater than the diameter of the semiconductor wafer W.That is, the susceptor 74 has a plane size greater than the plane sizeof the semiconductor wafer W. The susceptor 74 has a plurality of (thepresent preferred embodiment, five) guide pins 76 provided upright onthe upper surface. The five guide pins 76 are provided along thecircumference of a circle that is concentric with the outercircumferential circle of the susceptor 74. The diameter of the circlealong which the five guide pins 76 are located is slightly greater thanthe diameter of the semiconductor wafer W. Each guide pin 76 is alsomade of quartz. Note that the guide pins 76 may be processed integrallywith the susceptor 74 from a quartz ingot, or may be processedseparately from the susceptor 74 and attached to the susceptor 74 by,for example, welding.

The four connecting parts 72 provided upright on the base ring 71 andthe lower surface of the peripheral portion of the susceptor 74 arefixedly attached by welding. That is, the susceptor 74 and the base ring71 are fixedly coupled to each other by the connecting parts 72, makingthe holding part 7 an integral member of quartz. The base ring 71 ofthis holding part 7 is supported by the wall surface of the chamber 6,and thereby the holding part 7 is attached to the chamber 6. With theholding part 7 attached to the chamber 6, the generally disk-shapedsusceptor 74 is held in a horizontal position (position at which thenormal coincides with the vertical direction). The semiconductor wafer Wtransported into the chamber 6 is placed and held in a horizontalposition on the susceptor 74 of the holding part 7 attached to thechamber 6. By disposing the semiconductor wafer W inward of the circleformed by the five guide pins 76, a positional shift of thesemiconductor wafer in the horizontal direction is prevented. Note thatthe number of guide pins 76 is not limited to five, and may be anarbitrary number as long as the positional shift of the semiconductorwafer W is prevented.

As illustrated in FIGS. 2 and 3, the susceptor 74 has a verticallypenetrating opening 78 and a cut-out portion 77. The cut-out portion 77is formed to pass through the probe tip of a contact-type thermometer130 using a thermocouple. On the other hand, the opening 78 is formed toallow a radiation thermometer 120 to receive radiation (infrared light)applied from the lower surface of the semiconductor wafer W held by thesusceptor 74. The susceptor 74 further has four through holes 79 thatlift pins 12 of the transfer mechanism 10, which will be describedlater, pass through to transfer the semiconductor wafer W.

FIG. 5 is a plan view of the transfer mechanism 10, and FIG. 6 is a sideview of the transfer mechanism 10. The transfer mechanism 10 includestwo transfer arms 11. The transfer arms 11 have an arc shape thatextends generally along the annular recessed portion 62. The transferarms 11 each have two upright lift pins 12. Each transfer arm 11 ispivotable by a horizontal movement mechanism 13. The horizontal movementmechanism 13 horizontally moves the pair of transfer arms 11 between atransfer operation position (position indicated by the solid line inFIG. 5) at which the semiconductor wafer W is transferred to the holdingpart 7 and a retracted position (position indicated by the dasheddouble-dotted line in FIG. 5) at which the transfer arms 11 do notoverlap the semiconductor wafer W held by the holding part 7 in a planview. The horizontal movement mechanism 13 may be a mechanism forseparately pivoting the transfer arms 11 by individual motors, or amechanism for pivoting the pair of transfer arms 11 in conjunction witheach other by a single motor using a link mechanism.

The pair of transfer arms 11 are also movable upward and downward alongwith the horizontal movement mechanism 13 by an elevating mechanism 14.When the elevating mechanism 14 moves the pair of transfer arms 11upward at the transfer operation position, the four lift pins 12 passthrough the through holes 79 (see FIGS. 2 and 3) of the susceptor 74,and the upper ends of the lift pins 12 protrude from the upper surfaceof the susceptor 74. On the other hand, when the elevating mechanism 14moves the pair of transfer arms 11 down at the transfer operationposition to pull the lift pins 12 out of the through holes 79 and thenthe horizontal movement mechanism 13 moves the pair of transfer arms 11to open the transfer arms 11, each transfer arm 11 is moved to itsretracted position. The retracted positions of the pair of transfer arms11 are directly above the base ring 71 of the holding part 7. Since thebase ring 71 is placed on the bottom surface of the recessed portion 62,the retracted positions of the transfer arms 11 are on the inside of therecessed portion 62. Note that an exhaust mechanism (not shown) is alsoprovided in the vicinity of the area where the driving part (thehorizontal movement mechanism 13 and the elevating mechanism 14) of thetransfer mechanism 10 is provided to allow the atmosphere around thedriving part of the transfer mechanism 10 to be exhausted to the outsideof the chamber 6.

Referring back to FIG. 1, the flash heating part 5 provided above thechamber 6 includes, inside a casing 51, a light source that includes aplurality of (in the present preferred embodiment, 30) built-in xenonflash lamps FL, and a reflector 52 provided to cover the top of thelight source. The casing 51 of the flash heating part 5 also has a lamplight irradiation window 53 attached to the bottom. The lamp lightirradiation window 53, which forms the floor of the flash heating part5, is a plate-like quartz window made of quartz. Since the flash heatingpart 5 is located above the chamber 6, the lamp light irradiation window53 opposes the upper chamber window 63. The flash lamps FL emit flashlight from above the chamber 6 through the lamp light irradiation window53 and the upper chamber window 63 to the heat treatment space 65.

The flash lamps FL are each a rod-shaped lamp having an elongatedcylindrical shape and are arrayed in a plane such that theirlongitudinal directions are parallel to one another along the majorsurface of the semiconductor wafer W held by the holding part 7 (i.e.,along the horizontal direction). Thus, the plane formed by the array ofthe flash lamps FL is also a horizontal plane.

The xenon flash lamps FL each include a rod-shaped glass tube (dischargetube) and a trigger electrode provided on the outer circumferentialsurface of the glass tube, the glass tube containing a xenon gas sealedtherein and including an anode and a cathode that are disposed atopposite ends of the glass tube and connected to a capacitor. Since thexenon gas is electrically an insulator, no electricity passes throughthe glass tube in a normal state even if electric charge is stored inthe capacitor. However, if an electrical breakdown occurs due to theapplication of a high voltage to the trigger electrode, the electricitystored in the capacitor instantaneously flows through the glass tube,and light is emitted as a result of the excitation of xenon atoms ormolecules at that time. These xenon flash lamps FL have the propertiesof being capable of applying extremely intense light as compared with acontinuous lighting light source such as halogen lamps HL because theelectrostatic energy previously stored in the capacitor is convertedinto an extremely short optical pulse of 0.1 to 100 milliseconds.

The reflector 52 is provided above the flash lamps FL to cover all ofthe flash lamps FL. A basic function of the reflector 52 is to reflectthe flash light emitted from the flash lamps FL toward the heattreatment space 65. The reflector 52 is made of an aluminum alloy plate,and the surface (surface facing the flash lamps FL) of the reflector 52is roughened by blasting.

The halogen heating part 4 located below the chamber 6 includes aplurality of (in the present preferred embodiment, 40) build-in halogenlamps HL inside a casing 41. The halogen heating part 4 is a lightirradiation part that heats the semiconductor wafer W with the halogenlamps HL that emit light from below the chamber 6 through the lowerchamber window 64 to the heat treatment space 65.

FIG. 7 is a plan view illustrating the layout of the halogen lamps HL.In the first preferred embodiment, a plurality of halogen lamps HL arearranged in a region greater than the main surface (i.e., 300-mm circle)of the disk-shaped semiconductor wafer W held by the holding part 7. Thehalogen lamps HL are also arranged in a light source region that opposesthe lower main surface of the semiconductor wafer W.

As illustrated in FIGS. 1 and 7, in the first preferred embodiment, the40 halogen lamps HL are divided into and arranged in upper and lowerrows. The upper row closer to the holding part 7 includes an array of 20halogen lamps HL, and the lower row located further to the holding part7 than the upper row includes an array of 20 halogen lamps HL. Eachhalogen lamp HL is a rod-shaped lamp having an elongated cylindricalshape. The 20 halogen lamps HL in the upper row and the 20 halogen lampsHL in the lower row are respectively arranged such that theirlongitudinal directions are parallel to one another along the majorsurface of the semiconductor wafer W held by the holding part 7 (i.e.,in the horizontal direction). Thus, the plane formed by the array of thehalogen lamps HL in the upper row and the plane formed by the array ofthe halogen lamps HL in the lower row are both horizontal planes.

Also, a lamp group of the halogen lamps HL in the upper row and a lampgroup of the halogen lamps HL in the lower rows are arranged tointersect each other in grids. That is, the total of 40 halogen lamps HLare located such that the longitudinal direction of the 20 halogen lampsHL in the upper row and the longitudinal direction of the 20 halogenlamps HL in the lower row are orthogonal to each other.

The halogen lamps HL are filament-type light sources that pass currentthrough a filament disposed in the glass tube to make the filamentincandescent, thereby emitting light. Inside the glass tube is sealed agas prepared by introducing a trace amount of halogen element (e.g.,iodine or bromine) into an inert gas such as nitrogen or argon. Theintroduction of the halogen element allows the temperature of thefilament to be set at a high temperature while suppressing breakage ofthe filament. Thus, the halogen lamps HL have the properties of having alonger life than typical incandescent lamps and being capable ofcontinuously applying intense light. That is, the halogen lamps HL arecontinuous lighting lamps that continuously emit light for at least oneor more seconds. Moreover, the halogen lamps HL as rod-shaped lamps havea long life, and disposing theses halogen lamps HL in the horizontaldirection enhances the efficiently of radiation of the semiconductorwafer W located above the halogen lamps.

As illustrated in FIG. 7, in each of the upper and lower rows, thehalogen lamps HL are disposed at a higher density in the region thatopposes the peripheral portion of the semiconductor wafer W held by theholding part 7 than in the region that opposes the central portion ofthe semiconductor wafer W. That is, in each of the upper and lower rows,the halogen lamps HL are disposed at a shorter pitch in a peripheralportion 48 of the light source region than in a central portion 49thereof. In addition, the halogen lamps HL located in the peripheralportion 48 of the light source region have a higher filament windingdensity than the halogen lamps HL located in the central part 49. Thisconfiguration markedly increases the intensity of illumination from theperipheral portion 48 of the light source region, as compared with theintensity of illumination from the central part 49, and allows a greateramount of light to be applied to the peripheral portion of thesemiconductor wafer W where a temperature drop is likely to occur whenthe semiconductor wafer W is heated with the light emitted from thehalogen heating part 4.

The casing 41 of the halogen heating part 4 also includes a reflector 43under the two rows of halogen lamps HL (FIG. 1). The reflector 43reflects the light emitted from the halogen lamps HL to the heattreatment space 65.

The louver 21 and the light-shielding member 25 are provided between thehalogen heating part 4 and the holding part 7. FIG. 8 is a perspectiveview of the louver 21. The louver 21 is a cylindrical (bottomlesscylindrical) member with upper and lower opening ends. The louver 21 ismade of a material that is impervious to the light emitted from thehalogen lamps HL of the halogen heating part 4, and for example, made ofopaque quartz with a large number of superfine air bubbles contained inquartz glass. The size of the louver 21 may be appropriately optimizedfor the locations and configurations of the chamber 6 and the halogenheating part 4. The cylinder of the louver 21 only needs to have anouter diameter smaller than the light source region where the halogenlamps HL are located, and in the first preferred embodiment, forexample, the outer diameter of the louver 21 is 300 mm, which is thesame as the diameter of the semiconductor wafer W, and the innerdiameter of the louver 21 is 294 mm. The height of the louver 21 onlyneeds to be in the range of 15 to 25 mm (in the first preferredembodiment, 16 mm).

As illustrated in FIG. 1, a louver stage 22 is located on the upper endof the casing 41 of the halogen heating part 4. The louver stage 22 is aflat plate-like member made of quartz glass having transparency to thelight emitted from the halogen lamps HL. The louver 21 is installed onthe upper surface of this louver stage 22. The louver 21 is installedsuch that its cylinder has a central axis CX that passes through thecenter of the semiconductor wafer W held by the holding part 7. Thehalogen lamps HL of the halogen heating part 4 are arrayed in a regionthat opposes the lower surface of the semiconductor wafer W held by theholding part 7. Thus, the central axis CX of the louver 21 also passesthrough the center of the array of the halogen lamps HL.

With the cylindrical louver 21 of opaque quartz located between thehalogen heating part 4 and the chamber 6, light travelling from halogenlamps HL located outward of the louver 21 toward an inner region (i.e.,region located inward of the peripheral portion) of the semiconductorwafer W, which includes the vicinity of the central portion, is blockedoff by the wall surface of the opaque louver 21 during light emissionfrom the halogen lamps HL. On the other hand, light travelling fromhalogen lamps HL located outward of the louver 21 toward the peripheralportion of the semiconductor wafer W is not blocked. As a result, in thepresence of the louver 21, the amount of light travelling from thehalogen heating part 4 toward the peripheral portion of thesemiconductor wafer W is almost not reduced at all, whereas the amountof light travelling toward the inner region is reduced. Thus, the innerregion is weakly heated, and the peripheral portion of the semiconductorwafer W where a temperature drop is likely to occur is relativelystrongly heated.

However, the inventors of the present invention have newly found outafter active investigations that simply installing only the louver 21above the halogen heating part 4 may, on the contrary, increase thetemperature of a region that is located slightly inward of theperipheral portion of the semiconductor wafer W during light emissionfrom halogen lamps HL for heating. FIG. 14 illustrates a temperaturedistribution in the surface of the semiconductor wafer W when only thelouver 21 is installed. If only the louver 21 is simply installed andlight is emitted from the halogen lamps HL, overheat regions (hot spots)99 having higher temperatures than the other region appear slightlyinward of the peripheral portion of the semiconductor wafer W, asillustrated in FIG. 14. For example, when the semiconductor wafer W hasa diameter of 300 mm, such overheat regions 99 appear around within aradius of about 117 mm in the surface of the semiconductor wafer W. Thatis, the overheat regions 99 have an arc shape having a diameter of about235 mm.

In view of this, the present invention provides the light-shieldingmember 25, in addition to the louver 21, between the halogen heatingpart 4 and the holding part 7. FIG. 9 is a perspective view illustratingthe entire external appearances of the louver 21 and the light-shieldingmember 25 according to the first preferred embodiment. A ring stage 24is installed on the upper end of the cylindrical louver 21. The ringstage 24 is a disk-shaped member made of quartz glass havingtransparency to the light emitted from the halogen lamps HL. Thediameter of the ring stage 24 is the same as the outer diameter of thelouver 21 (in the present embodiment, 300 mm). The ring stage 24 has aplate thickness of 2 to 3 mm.

The light-shielding member 25 is disposed on the upper surface of thering stage 24. That is, in the first preferred embodiment, thelight-shielding member 25 is further disposed on the ring stage 24,which is a quartz plate provided on the louver 21. The light-shieldingmember 25 is an annular flat plate-like light-shielding ring. Thelight-shielding member 25 is made of a material that is impervious tothe light emitted from the halogen lamps HL of the halogen heating part4, and for example, made of opaque quartz with a large number ofsuperfine air bubbles contained in quartz glass. In the first preferredembodiment, the louver 21 and the light-shielding member 25 are made ofthe same material.

The outer diameter of the annular light-shielding member 25 is smallerthan the inner diameter of the cylindrical louver 21, and for example,280 mm. That is, the outer dimensions of the light-shielding member 25are smaller than the inner dimensions of the louver 21. Thelight-shielding member 25 has an inner diameter of, for example, 260 mm,and a plate thickness of, for example, 2 mm.

The central axis CX of the louver 21 coincides with the central axis ofthe annular light-shielding member 25. Thus, the light-shielding member25 is located such that its annular shape has a central axis that passesthrough the center of the semiconductor wafer W held by the holding part7.

Referring back to FIG. 1, the controller 3 controls various operatingmechanisms of the heat treatment apparatus 1 described above. Thehardware configuration of the controller 3 is similar to theconfiguration of a typical computer. That is, the controller 3 includesa CPU that is a circuit for performing various types of computations, aROM that is a read-only memory for storing basic programs, a RAM that isa readable/writable memory for storing various types of information, anda magnetic disk for storing software and data for control. Theprocessing of the heat treatment apparatus 1 is implemented by the CPUof the controller 3 executing predetermined processing programs.

The heat treatment apparatus 1 also includes, in addition to theabove-described constituent elements, various cooling structures inorder to prevent an excessive temperature increase in the halogenheating part 4, the flash heating part 5, and the chamber 6 due to heatenergy generated by the halogen lamps HL and the flash lamps FL duringheat treatment of the semiconductor wafer W. For example, a water-cooledtube (not shown) is provided in the wall of the chamber 6. The halogenheating part 4 and the flash heating part 5 also have an air coolingstructure that forms a gas flow in its interior to exhaust heat. Also,air is supplied to the clearance between the upper chamber window 63 andthe lamp light irradiation window 53 to cool the flash heating part 5and the upper chamber window 63.

Next, the procedure of processing performed on the semiconductor wafer Wby the heat treatment apparatus 1 will be described. The semiconductorwafer W to be processed here is a semiconductor substrate doped withimpurities (ions) by ion implantation. These impurities are activatedthrough heat treatment (annealing) involving the application of flashlight by the heat treatment apparatus 1. The following procedure ofprocessing performed by the heat treatment apparatus 1 is implemented bythe controller 3 controlling each operating mechanism of the heattreatment apparatus 1.

First, the valve 84 for supplying a gas and the valves 89 and 192 forexhausting a gas are opened to start the supply and exhaust of a gasinto and from the chamber 6. When the valve 84 is opened, a nitrogen gasis supplied from the gas supply port 81 into the heat treatment space65. When the valve 89 is opened, the gas in the chamber 6 is exhaustedfrom the gas exhaust port 86. Thereby, the nitrogen gas supplied fromabove the heat treatment space 65 in the chamber 6 flows down and isexhausted from below the heat treatment space 65.

When the valve 192 is opened, the gas in the chamber 6 is also exhaustedfrom the transport opening 66. Moreover, the atmosphere around thedriving part of the transfer mechanism 10 is also discharged by anexhaust mechanism (not shown). During the heat treatment of thesemiconductor wafer W in the heat treatment apparatus 1, the nitrogengas continues to be supplied into the heat treatment space 65, and theamount of the nitrogen gas supplied is changed as appropriate inaccordance with the processing step.

Then, the gate valve 185 is opened to open the transport opening 66, andthe ion-implanted semiconductor wafer W is transported into the heattreatment space 65 of the chamber 6 through the transport opening 66 bya transport robot located outside the apparatus. The semiconductor waferW transported into the heat treatment space 65 by the transport robot ismoved to a position directly above the holding part 7 and stopped. Then,the pair of transfer arms 11 of the transfer mechanism 10 moveshorizontally from the retracted position to the transfer operationposition and moves upward, so that the lift pins 12 pass through thethrough holes 79 and protrude from the upper surface of the susceptor 74to receive the semiconductor wafer W.

After the semiconductor wafer W is placed on the lift pins 12, thetransport robot retracts from the heat treatment space 65, and thetransport opening 66 is closed with the gate valve 185. Then, the pairof transfer arms 11 moves down, and thereby the semiconductor wafer W istransferred from the transfer mechanism 10 to the susceptor 74 of theholding part 7 and held in a horizontal position from the underside. Thesemiconductor wafer W is held by the holding part 7 with itsimpurity-doped surface with a pattern facing upward. The semiconductorwafer W is also held inward of the five guide pins 76 on the uppersurface of the susceptor 74. The two transfer arms 11 that have moveddown to positions below the susceptor 74 are retracted to theirretracted positions, i.e., to the inside of the recessed portion 62, bythe horizontal movement mechanism 13.

After the semiconductor wafer W is held in a horizontal position fromthe underside by the holding part 7 made of quartz, all of the 40halogen lamps HL of the halogen heating part 4 are turned on in unisonto start preheating (assist-heating). The halogen light emitted from thehalogen lamps HL passes through the louver stage 22, the ring stage 24,the lower chamber window 64, and the susceptor 74, which are made ofquartz, and is applied from the rear surface (main surface on theopposite side to the front surface) of the semiconductor wafer W. Thesemiconductor wafer W that has received the light emitted from thehalogen lamps HL is preheated, and thereby the temperature of thesemiconductor wafer W increases. Note that the transfer arms 11 of thetransfer mechanism 10 that have retracted to the inside of the recessedportion 62 do not impede the heating with the halogen lamps HL.

During preheating with the halogen lamps HL, the temperature of thesemiconductor wafer W is measured with the contact-type thermometer 130.Specifically, the contact-type thermometer 130 with a built-inthermocouple is brought into contact with the lower surface of thesemiconductor wafer W held by the holding part 7 through the cut-outportion 77 of the susceptor 74 and measures the increasing wafertemperature. The measured temperature of the semiconductor wafer W istransmitted to the controller 3. The controller 3 monitors whether thetemperature of the semiconductor wafer W that is increasing due to theapplication of light from the halogen lamps HL has reached apredetermined preheating temperature T1. The preheating temperature T1is set to about 200° C. to 800° C. at which the impurities doped in thesemiconductor wafer W are not caused to be diffused by heat, andpreferably, may be set to about 350° C. to 600° C. (in the presentembodiment, 600° C.). Note that when the temperature of thesemiconductor wafer W is increased by the application of light from thehalogen lamps HL, the radiation thermometer 120 does not measure thetemperature. This is because accurate temperature measurement isdifficult due to the halogen light from the halogen lamps HL enteringthe radiation thermometer 120 as disturbance light.

In the first preferred embodiment, the opaque cylindrical louver 21 andthe annular light-shielding member 25 are provided between the halogenheating part 4 and the chamber 6 and blocks off part of the lighttravelling from the halogen heating part 4 toward the semiconductorwafer W held by the holding part 7. FIG. 10 illustrates how the opticalpath is controlled by the louver 21 and the light-shielding member 25according to the first preferred embodiment.

As described above, in the present embodiment, the halogen lamps HL aredisposed in the region greater than the main surface of the disk-shapedsemiconductor wafer W, and the outer diameter of the louver 21 is thesame as the diameter of the semiconductor wafer W. Thus, some of thehalogen lamps HL are located outward of the cylindrical louver 21. Thisconfiguration allows the light travelling from the halogen lamps HLlocated outward of the louver 21 toward the inner region (region locatedinward of the peripheral portion) of the semiconductor wafer W,including the vicinity of the central portion, to be blocked off by thewall surface of the opaque louver 21. On the other hand, the lighttravelling from the halogen lamps HL located outward of the louver 21toward the peripheral portion of the semiconductor wafer W is notblocked.

Also, the central axis of the annular light-shielding member 25coincides with the central axis CX of the louver 21, and the outerdiameter of the light-shielding member 25 is smaller than the innerdiameter of the louver 21. Thus, a clearance that allows the lightemitted from the halogen lamps HL to transmit is present between theinner wall surface of the louver 21 and the outer circumference of thelight-shielding member 25 as illustrated in FIG. 10. In the firstpreferred embodiment in which the louver 21 has an inner diameter of 294mm and the light-shielding member 25 has an outer diameter of 280 mm, a7-mm wide annular clearance is created between the inner wall surface ofthe louver 21 and the outer circumference of the light-shielding member25. The clearance is located immediately under the peripheral portion ofthe semiconductor wafer W because the outer diameter of the louver 21 isthe same as the diameter of the semiconductor wafer W held by theholding part 7. Accordingly, as illustrated in FIG. 10, the lightemitted from the halogen lamps HL and passing through the clearancebetween the inner wall surface of the louver 21 and the outer peripheryof the light-shielding member 25 is applied to the peripheral portion ofthe semiconductor wafer W held by the holding part 7. Thisconfiguration, combined with the light-shielding effect of the louver 21described above, relatively increases the intensity of illumination ofthe peripheral portion of the semiconductor wafer W with the lightemitted from the halogen lamps HL and allows the peripheral portionwhere a temperature drop is likely to occur to be strongly heated.

On the other hand, the opaque annular light-shielding member 25 havingan outer diameter of 280 mm and an inner diameter of 260 mm is locatedbelow a region that is slightly inward of the peripheral portion of thesemiconductor wafer W held by the holding part 7, i.e., below theoverheat regions 99 in FIG. 14 that appear when only the louver 21 isinstalled. Thus, the light emitted from the halogen lamps HL andtravelling toward the overheat regions 99 located slightly inward of theperipheral portion of the semiconductor wafer W is blocked off by thelight-shielding member 25 as illustrated in FIG. 10. This configurationrelatively reduces the intensity of illumination of the overheat regions99 of the semiconductor wafer W, which appear when only the louver 21 isinstalled, and reduces the application of heat to the overheat regions99.

In this way, the combination of the louver 21 and the light-shieldingmember 25 increases the intensity of illumination of the peripheralportion of the semiconductor wafer W with the light emitted from thehalogen lamps HL, and at the same time, reduces the intensity ofillumination of the overheat regions 99 that are located slightly inwardof the peripheral portion of the semiconductor wafer W. As a result, theperipheral portion of the semiconductor wafer W where a temperature dropis likely to occur is relatively strongly heated, and the overheatregions 99 located slightly inward of the peripheral portion and havinga temperature that may increase excessively when only the louver 21 isinstalled is relatively weakly heated. This configuration effectivelyresolves unevenness of the temperature distribution in the surface ofthe semiconductor wafer W during preheating.

When a predetermined amount of time has elapsed after the temperature ofthe semiconductor wafer W reached the preheating temperature T1, flashlight is applied from the flash lamps FL of the flash heating part 5 tothe surface of the semiconductor wafer W. At this time, part of theflash light emitted from the flash lamps FL travels directly into thechamber 6, and part of the flash light is reflected by the reflector 52and then travels into the chamber 6. The application of such flash lightenables flash heating of the semiconductor wafer W.

The flash heating implemented by the application of flash light from theflash lamps FL allows the surface temperature of the semiconductor waferW to be increased in a short time. That is, the flash light emitted fromthe flash lamps FL is extremely short intense flash light that isobtained by converting the electrostatic energy previously stored in thecapacitor into an extremely short optical pulse and that has anirradiation time of about 0.1 to 100 milliseconds. The surfacetemperature of the semiconductor wafer W heated with the flash lightemitted from the flash lamps FL instantaneously rises to a treatmenttemperature T2 of 1000° C. or higher, and then drops rapidly after theactivation of impurities doped in the semiconductor wafer W. In thisway, the heat treatment apparatus 1 allows the surface temperature ofthe semiconductor wafer W to rise and drop in an extremely short time,and thereby enables the activation of impurities doped in thesemiconductor wafer W while suppressing the diffusion of impurities dueto heat. Since the time required for the activation of impurities isextremely shorter than the time required for heat diffusion ofimpurities, the activation is completed even in such a short time ofabout 0.1 to 100 milliseconds that causes no diffusion.

In the first preferred embodiment, the louver 21 and the light-shieldingmember 25 block off part of the light travelling from the halogenheating part 4 toward the inner region (in particular, overheat regions99) of the semiconductor wafer W to make uniform the temperaturedistribution in the surface of the semiconductor wafer W at thepreheating stage. This configuration also allows the temperaturedistribution in the surface of the semiconductor wafer W to be uniformduring the application of flash light.

After the flash heating process is completed and a predetermined periodof time has elapsed, the halogen lamps HL are turned off. Thetemperature of the semiconductor wafer W thus rapidly drops from thepreheating temperature T1. The decreasing temperature of thesemiconductor wafer W is measured with the contact-type thermometer 130or the radiation thermometer 120, and the measurement result istransmitted to the controller 3. On the basis of the measurement result,the controller 3 monitors whether the temperature of the semiconductorwafer W has dropped to a predetermined temperature. After thetemperature of the semiconductor wafer W has dropped to thepredetermined temperature or less, the two transfer arms 11 of thetransfer mechanism 10 are moved horizontally again from the retractedpositions to the transfer operation position and moved upward, so thatthe lift pins 12 protrude from the upper surface of the susceptor 74 andreceive the heat-treated semiconductor wafer W from the susceptor 74.Then, the transport opening 66 closed by the gate valve 185 is openedand the semiconductor wafer W placed on the lift pins 12 is transportedout of the apparatus by the transport robot. This completes the heattreatment of the semiconductor wafer W in the heat treatment apparatus1.

In the first preferred embodiment, the opaque cylindrical louver 21 andthe annular light-shielding member 25 are provided between the halogenheating part 4 and the chamber 6 to control the optical path of thelight travelling from the halogen heating part 4 toward thesemiconductor wafer W held by the holding part 7. As describedpreviously, in the case where preheating by the halogen heating part 4is conducted with only the louver 21 installed, the overheat regions 99having higher temperatures than the other region tend to appear slightlyinward of the peripheral portion of the semiconductor wafer W. In viewof this, the light-shielding member 25 is also provided, in addition tothe louver 21, to block off the light travelling toward the overheatregions 99, which are located slightly inward of the peripheral portionof the semiconductor wafer W. This configuration allows the temperaturedistribution in the surface of the semiconductor wafer W to be uniformduring preheating and consequently allows the temperature distributionin the surface of the semiconductor wafer W to be uniform during flashheating.

Second Preferred Embodiment

Next, a second preferred embodiment according to the present inventionwill be described. The overall configuration of a heat treatmentapparatus of the second preferred embodiment is approximately the sameas the configuration of the first preferred embodiment. The procedure ofprocessing performed on the semiconductor wafer W in the secondpreferred embodiment is also the same as the procedure in the firstpreferred embodiment. The second preferred embodiment is different fromthe first preferred embodiment in the shape of a light-shielding member.

FIG. 11 is a plan view of a light-shielding member 125 of the secondpreferred embodiment. While the light-shielding member 25 of the firstpreferred embodiment is an annular flat plate-like light-shielding ring,the light-shielding member 125 of the second preferred embodiment is asquare plate-like member having a square hole in the center. Thelight-shielding member 125 of the second preferred embodiment can alsobe called an annular flat plate-like member. As in the first preferredembodiment, the light-shielding member 125 is made of a material that isimpervious to the light emitted from the halogen lamps HL of the halogenheating part 4, and for example, made of opaque quartz with a largenumber of superfine air bubbles contained in quartz glass.

The length of a diagonal line of the square light-shielding member 125is smaller than the inner diameter of the cylindrical louver 21. Thelight-shielding member 125 has a plate thickness of, for example, 2 mm.This light-shielding member 125 is disposed on the upper surface of thering stage 24 provided on the upper end of the cylindrical louver 21.The rest of the configuration of the second preferred embodiment,excluding the shape of the light-shielding member 125, is the same asthe configuration of the first preferred embodiment.

In the second preferred embodiment, when the semiconductor wafer W ispreheated by the application of light from the halogen heating part 4,light emitted from the halogen lamps HL and passing through theclearance between the inner wall surface of the louver 21 and the outercircumference of the light-shielding member 125 is applied to theperipheral portion of the semiconductor wafer W held by the holding part7. On the other hand, light emitted from the halogen lamps HL andtravelling toward the region of the semiconductor wafer W located inwardof the peripheral portion is blocked off by the light-shielding member125. This allows the temperature distribution in the surface of thesemiconductor wafer W to be uniform during preheating and consequentlyallows the temperature distribution in the surface of the semiconductorwafer W to be uniform during flash heating, as in the first preferredembodiment.

In particular, when preheating by the halogen heating part 4 isconducted with only the louver 21 installed, overheat regions thatappear in the surface of the semiconductor wafer W and have highertemperatures than the other region may have a shape as illustrated inFIG. 11. In this case, the temperature distribution in the surface ofthe semiconductor wafer W is effectively made uniform by thelight-shielding member 125 of the second preferred embodiment blockingoff the light travelling toward the overheat regions.

Third Preferred Embodiment

Next, a third preferred embodiment of the present invention will bedescribed. The overall configuration of a heat treatment apparatus ofthe third preferred embodiment is approximately the same as theconfiguration of the first preferred embodiment. The procedure ofprocessing performed on the semiconductor wafer W in the third preferredembodiment is also the same as the procedure of the first preferredembodiment. The third preferred embodiment is different from the firstpreferred embodiment in the shape of a light-shielding member.

FIG. 12 is a plan view of a light-shielding member 225 of the thirdpreferred embodiment. The light-shielding member 225 of the thirdpreferred embodiment is configured by a plurality of light-shieldingparts, with four plate-like light-shielding pieces 222 being locatedinward of an annular flat plate-like light-shielding ring 221. Thelight-shielding ring 221 and the four light-shielding pieces 222, whichconstitute the light-shielding member 225, are made of a material thatis impervious to the light emitted from the halogen lamps HL of thehalogen heating part 4, and for example, made of opaque quartz with alarge number of superfine air bubbles contained in quartz glass.

The light-shielding ring 221 is similar to the light-shielding member 25of the first preferred embodiment. That is, the outer diameter of thelight-shielding ring 221 is smaller than the inner diameter of thecylindrical louver 21. Each light-shielding piece 222 is a rectangularplate-like member having dimensions that allows the light-shieldingpiece 222 to be located within the light-shielding ring 221. Thelight-shielding ring 221 and the four light-shielding pieces 222 aredisposed in the layout as illustrated in FIG. 12 on the upper surface ofthe ring stage 24 provided on the upper end of the cylindrical louver21. The rest of the configuration of the third preferred embodiment,excluding the shape of the light-shielding member 225, is the same asthe configuration of the first preferred embodiment.

In the third preferred embodiment, when the semiconductor wafer W ispreheated by the application of light from the halogen heating part 4,light emitted from the halogen lamps HL and passing through theclearance between the inner wall surface of the louver 21 and the outercircumference of the light-shielding ring 221 is applied to theperipheral portion of the semiconductor wafer W held by the holding part7. On the other hand, part of the light emitted from the halogen lampsHL and travelling toward the region of the semiconductor wafer W locatedinward of the peripheral portion is blocked off by the light-shieldingring 221 and the light-shielding pieces 222. This configuration allowsthe temperature distribution in the surface of the semiconductor wafer Wto be uniform during preheating and consequently allows the temperaturedistribution in the surface of the semiconductor wafer W to be uniformduring flash heating, as in the first preferred embodiment.

In particular, when preheating by the halogen heating part 4 isconducted with only the louver 21 installed, not only overheat regions99 having a shape as illustrated in FIG. 14 but also other overheatregions may also appear inward of the overheat regions 99 in the surfaceof the semiconductor wafer W. In this case, light travelling towardthose overheat regions is separately blocked off by the light-shieldingpieces 222 provided in addition to the light-shielding ring 221 as inthe third preferred embodiment. This configuration allows thetemperature distribution in the surface of the semiconductor wafer W tobe effectively uniform.

Fourth Preferred Embodiment

Next, a fourth preferred embodiment of the present invention will bedescribed. The overall configuration of a heat treatment apparatus ofthe fourth preferred embodiment is approximately the same as theconfiguration of the first preferred embodiment. The procedure ofprocessing performed on the semiconductor wafer W in the fourthpreferred embodiment is also the same as the procedure of the firstpreferred embodiment. The fourth preferred embodiment is different fromthe first preferred embodiment in the shape of a light-shielding member.

FIG. 13 is a plan view of a light-shielding member 325 of the fourthpreferred embodiment. The light-shielding member 325 of the fourthpreferred embodiment is configured by a plurality of light-shieldingparts, with a plate-like light-shielding piece 322 disposed inward of aflat square frame-like light-shielding frame 321. The light-shieldingframe 321 and the light-shielding piece 322, which constitute thelight-shielding member 325, is made of a material that is impervious tothe light emitted from the halogen lamps HL of the halogen heating part4, and for example, made of opaque quartz with a large number ofsuperfine air bubbles contained in quartz glass.

The length of a diagonal line of the square frame-like light-shieldingframe 321 is smaller than the inner diameter of the cylindrical louver21. The light-shielding piece 322 is a disk-shaped member havingdimensions that allow the light-shielding piece 322 to be located withinthe light-shielding frame 321. The light-shielding frame 321 and thelight-shielding piece 322 are disposed in the layout as illustrated inFIG. 13 on the upper surface of the ring stage 24 provided on the upperend of the cylindrical louver 21. The rest of the configuration of thefourth preferred embodiment, excluding the shape of the light-shieldingmember 325, is the same as the configuration of the first preferredembodiment.

In the fourth preferred embodiment, when the semiconductor wafer W ispreheated by the application of light from the halogen heating part 4,light emitted from the halogen lamps HL and passing through theclearance between the inner wall surface of the louver 21 and the outerperiphery of the light-shielding frame 321 is applied to the peripheralportion of the semiconductor wafer W held by the holding part 7. On theother hand, part of the light emitted from the halogen lamps HL andtravelling toward the region of the semiconductor wafer W that islocated inward of the peripheral portion is blocked off by thelight-shielding frame 321 and the light-shielding piece 322. Thisconfiguration allows the temperature distribution in the surface of thesemiconductor wafer W to be uniform during preheating and consequentlyallows the temperature distribution in the surface of the semiconductorwafer W to be uniform during flash heating, as in the first preferredembodiment.

In particular, when preheating by the halogen heating part 4 isconducted with only the louver 21 installed, not only the overheatregions 99 having a shape as illustrated in FIG. 14 but also otheroverheat regions may also appear inward of the overheat regions 99 inthe surface of the semiconductor wafer W. In this case, light travellingtoward those overheat regions is separately blocked off by thelight-shielding piece 322 provided in addition to the light-shieldingframe 321 as in the fourth preferred embodiment. This configurationallows the temperature distribution in the surface of the semiconductorwafer W to be effectively uniform.

Fifth Preferred Embodiment

Next, a fifth preferred embodiment of the present invention will bedescribed. FIG. 15 illustrates the layout of a louver 21 and alight-shielding member 25 according to the fifth preferred embodiment.In FIG. 15, constituent elements that are the same as the constituentelements of the first preferred embodiment are given the same referencenumerals. While the light-shielding member 25 of the first preferredembodiment is located on the ring stage 24 provided on the louver 21,the light-shielding member 25 of the fifth preferred embodiment islocated on the lower chamber window 64 of the chamber 6 that opposes thehalogen heating part 4. The rest of the configuration of the fifthpreferred embodiment, excluding the location of the light-shieldingmember 25, and the procedure of processing performed on thesemiconductor wafer W are the same as the configuration and procedure ofthe first preferred embodiment.

As in the first preferred embodiment, the louver 21 is provided on thelouver stage 22 such that its cylinder has a central axis that passesthrough the center of the semiconductor wafer W held by the holding part7. The light-shielding member 25 is located on the lower chamber window64 such that its annular shape has a central axis that passes throughthe center of the semiconductor wafer W held by the holding part 7. Thematerials and shapes of the louver 21 and the light-shielding member 25are the same as the material and shape of the first preferredembodiment. Specifically, the louver 21 and the light-shielding member25 are both made of a material (e.g., opaque quartz) that is imperviousto the light emitted from the halogen lamps HL, and the outer diameterof the light-shielding member 25 is smaller than the inner diameter ofthe louver 21.

As illustrated in FIG. 15, light emitted from the halogen lamps HL andpassing through the clearance between the inner wall surface of thelouver 21 and the outer circumference of the light-shielding member 25is applied to the peripheral portion of the semiconductor wafer W heldby the holding part 7. This configuration relatively increases theintensity of illumination of the peripheral portion of the semiconductorwafer W with the light emitted from the halogen lamps HL, and therebythe peripheral portion where a temperature drop is likely to occur isstrongly heated.

On the other hand, as in the first preferred embodiment, thelight-shielding member 25 is present below the region of thesemiconductor wafer W that is located slightly inward of the peripheralportion of the semiconductor wafer W held by the holding part 7. Thus,the light emitted from the halogen lamps HL and travelling toward theregion of the semiconductor wafer W that is located slightly inward ofthe peripheral portion is blocked off by the light-shielding member 25as illustrated in FIG. 15. This configuration relatively reduces theintensity of illumination of overheat regions 99 of semiconductor waferW that may appear when only the louver 21 is installed, and thereby theoverheat regions 99 are weakly heated.

In this way, the combination of the louver 21 and the light-shieldingmember 25 increases the intensity of illumination of the peripheralportion of the semiconductor wafer W with the light emitted from thehalogen lamps HL, and at the same time, reduces the intensity ofillumination of the region located slightly inward of the peripheralportion. As a result, the peripheral portion of the semiconductor waferW where a temperature drop is likely to occur is relatively stronglyheated, whereas the region located slightly inward of the peripheralportion and in which the temperature tends to increase with installationof only the louver 21 is relatively weakly heated. This configurationallows the temperature distribution in the surface of the semiconductorwafer W to be uniform during preheating.

Sixth Preferred Embodiment

Next, a sixth preferred embodiment of the present invention will bedescribed. FIG. 16 illustrates the layout of a louver 21 and alight-shielding member 25 according to the sixth preferred embodiment.In FIG. 16, constitute elements that are the same as the constituentelements of the first preferred embodiment are given the same referencenumerals. While the light-shielding member 25 of the first preferredembodiment is located on the ring stage 24 provided on the louver 21,the light-shielding member 25 of the sixth preferred embodiment islocated on a louver stage 22 on which the louver 21 is also located. Therest of the configuration of the sixth preferred embodiment, excludingthe location of the light-shielding member 25, and the procedure ofprocessing performed on the semiconductor wafer W are the same as theconfiguration and procedure of the first preferred embodiment.

As in the first preferred embodiment, the louver 21 is also provided onthe louver stage 22 such that its cylinder has a central axis thatpasses through the center of the semiconductor wafer W held by theholding part 7. The light-shielding member 25 is also provided on thelouver stage 22 such that its annular shape has a central axis thatpasses through the center of the semiconductor wafer W held by theholding part 7. As illustrated in FIG. 16, the light-shielding member 25is located inward of the cylindrical louver 21 on the louver stage 22 ofquartz on which the louver 21 is located. The materials and shapes ofthe louver 21 and the light-shielding member 25 are the same as thematerial and shape of the first preferred embodiment. Specifically, thelouver 21 and the light-shielding member 25 are both made of a material(e.g., opaque quartz) that is impervious to the light emitted from thehalogen lamps HL, and the outer diameter of the light-shielding member25 is smaller than the inner diameter of the louver 21.

As illustrated in FIG. 16, light emitted from the halogen lamps HL andpassing through the clearance between the inner wall surface of thelouver 21 and the outer circumference of the light-shielding member 25is applied to the peripheral portion of the semiconductor wafer W heldby the holding part 7. This configuration relatively increases theintensity of illumination of the peripheral portion of the semiconductorwafer W with the light emitted from the halogen lamps HL, and therebythe peripheral portion where a temperature drop is likely to occur isstrongly heated.

On the other hand, the light-shielding member 25 is present below theregion of the semiconductor wafer W that is located slightly inward ofthe peripheral portion of the semiconductor wafer W held by the holdingpart 7, as in the first preferred embodiment. Thus, light emitted fromthe halogen lamps HL and travelling toward the region of thesemiconductor wafer W that is located slightly inward of the peripheralportion is blocked off by the light-shielding member 25 as illustratedin FIG. 16. This configuration relatively reduces the intensity ofillumination of overheat regions 99 of the semiconductor wafer W thatmay appear when only the louver 21 is installed, and thereby theoverheat regions 99 are weakly heated.

In this way, the combination of the louver 21 and the light-shieldingmember 25 increases the intensity of illumination of the peripheralportion of the semiconductor wafer W with the light emitted from thehalogen lamps HL, and at the same time, reduces the intensity ofillumination of the region located slightly inward of the peripheralportion. As a result, the peripheral portion of the semiconductor waferW where a temperature drop is likely to occur is relatively stronglyheated, whereas the region located slightly inward of the peripheralportion and in which the temperature tends to increase with installationof only the louver 21 is relatively weakly hated. This configurationallows the temperature distribution in the surface of the semiconductorwafer W to be uniform during preheating.

Seventh Preferred Embodiment

Next, a seventh preferred embodiment of the present invention will bedescribed. FIG. 17 illustrates the layout of louvers 28 and 29 and alight-shielding member 25 according to the seventh preferred embodiment.In FIG. 17, constitute elements that are the same as the constituentelements of the first preferred embodiment are given the same referencenumerals. While the light-shielding member 25 of the first preferredembodiment is located on the ring stage 24 provided on the louver 21,the light-shielding member 25 of the seventh preferred embodiment islocated on the ring stage 24 that is sandwiched between the upper andlower louvers 28 and 29. The rest of the configuration of the seventhpreferred embodiment, excluding the location of the light-shieldingmember 25, and the procedure of processing performed on thesemiconductor wafer W are the same as the configuration and procedure ofthe first preferred embodiment.

In the seventh preferred embodiment, a louver is divided into upper andlower parts, i.e., the upper louver 29 and the lower louver 28. Like thelouver 21 of the first preferred embodiment, the upper louver 29 and thelower louver 28 are both made of a material (e.g., opaque quartz) thatis impervious to the light emitted from the halogen lamps HL. The outerdiameters and inner diameters of the upper louver 29 and the lowerlouver 28 are respectively the same as the outer diameter and innerdiameter of the louver 21 of the first preferred embodiment. Note thatthe heights of the upper louver 29 and the lower louver 28 may be set toan appropriate value.

The ring stage 24 is located to be sandwiched between the upper louver29 and the lower louver 28. In other words, as in the first preferredembodiment, the ring stage 24 is located on the upper end of thecylindrical lower louver 28, and the cylindrical upper louver 29 made ofthe same material and having the same outer and inner diameters as thelower louver 28 is further located on the ring stage 24. Then, thelight-shielding member 25 is located on the upper surface of the ringstage 24.

The upper louver 29 and the lower louver 28 are stacked on top of eachother such that their cylinders have a central axis that passes throughthe center of the semiconductor wafer W held by the holding part 7. Thelight-shielding member 25 is also provided on the ring stage 24 suchthat its annular shape has a central axis that passes through the centerof the semiconductor wafer W held by the holding part 7. Thelight-shielding member 25 is also made of a material (e.g., opaquequartz) that is impervious to the light emitted from the halogen lampsHL, and the outer diameter of the light-shielding member 25 is smallerthan the inner diameters of the upper louver 29 and the lower louver 28.

As illustrated in FIG. 17, light emitted from the halogen lamps HL andpassing through the clearance between the inner wall surfaces of theupper louver 29 and the lower louver 28 and the outer circumference ofthe light-shielding member 25 is applied to the peripheral portion ofthe semiconductor wafer W held by the holding part 7. This configurationrelatively increases the intensity of illumination of the peripheralportion of the semiconductor wafer W with the light emitted from thehalogen lamps HL, and thereby the peripheral portion where a temperaturedrop is likely to occur is strongly heated.

On the other hand, as in the first preferred embodiment, thelight-shielding member 25 is present below the region of thesemiconductor wafer W that is located slightly inward of the peripheralportion of the semiconductor wafer W held by the holding part 7. Thus,light emitted from the halogen lamps HL and travelling toward the regionof the semiconductor wafer W located slightly inward of the peripheralportion is blocked off by the light-shielding member 25 as illustratedin FIG. 17. This configuration relatively reduces the intensity ofillumination of overheat regions 99 of the semiconductor wafer W thatmay appear when only the louver 21 is installed, and thereby theoverheat regions 99 are weakly heated.

In this way, the combination of the upper louver 29, the lower louver28, and the light-shielding member 25 increases the intensity ofillumination of the peripheral portion of the semiconductor wafer W withthe light emitted from the halogen lamps HL, and at the same time,reduces the intensity of illumination of the region located slightlyinward of the peripheral portion. As a result, the peripheral portion ofthe semiconductor wafer W where a temperature drop is likely to occur isrelatively strongly heated, and the region located slightly inward ofthe peripheral portion and in which the temperature tends to increasewith installation of only the louver 21 is relatively weakly heated.This configuration allows the temperature distribution in the surface ofthe semiconductor wafer W to be uniform during preheating.

Eighth Preferred Embodiment

Next, an eighth preferred embodiment of the present invention will bedescribed. FIG. 18 is a longitudinal cross-sectional view of aconfiguration of a heat treatment apparatus 1 a according to the eighthpreferred embodiment. The heat treatment apparatus 1 a of the eighthpreferred embodiment is also a flash-lamp annealing apparatus forheating a disk-shaped semiconductor wafer W having a diameter of 300 mmas a substrate by irradiating the semiconductor wafer W with flashlight. In FIG. 18, constituent elements that are the same as theconstituent elements of the first preferred embodiment are given thesame reference numerals. The eighth preferred embodiment is differentfrom the first preferred embodiment in that two louvers, namely an outerlouver 121 and an inner louver 123, are provided between the halogenheating part 4 and the chamber 6.

FIG. 19 is a perspective view of the outer louver 121 and the innerlouver 123. The outer louver 121 and the inner louver 123 are bothcylindrical (bottomless cylindrical) members having upper and loweropening ends. The outer louver 121 and the inner louver 123 are made ofa material that is impervious to the light emitted from the halogenlamps HL of the halogen heating part 4, and for example, made of opaquequartz with a large number of superfine air bubbles contained in quartzglass.

As illustrated in FIG. 18, the louver stage 22 is provided on the upperend of the casing 41 of the halogen heating part 4. The louver stage 22is a flat plate-like member made of quartz glass having transparency tothe light emitted from the halogen lamps HL. The outer louver 121 andthe inner louver 123 are located on the upper surface of this louverstage 22. That is, the outer louver 121 and the inner louver 123 arelocated below the lower chamber window 64 outside the chamber 6.

The outer louver 121 and the inner louver 123 are located such thattheir cylinders have a central axes CX that passes through the center ofthe semiconductor wafer W held by the holding part 7. That is, the outerlouver 121 and the inner louver 123 are concentrically arranged on thelouver stage 22 in a plan view. The halogen lamps HL of the halogenheating part 4 are arrayed in a region that opposes the lower surface ofthe semiconductor wafer W held by the holding part 7. Thus, the centralaxis CX of the outer louver 121 and the inner louver 123 also passesthrough the center of the array of the halogen lamps HL.

The diameter of the cylinder of the outer louver 121 is greater than thediameter of the semiconductor wafer W. In the present embodiment, forexample, the outer louver 121 has an outer diameter of 323 mm and aninner diameter of 317 mm. That is, the diameter of the outer louver 121at the central part of the plate thickness of the cylindrical wall is320 mm.

On the other hand, the diameter of the cylinder of the inner louver 123is smaller than the diameter of the semiconductor wafer W. In thepresent embodiment, for example, the inner louver 123 has an outerdiameter of 283 mm and an inner diameter of 277 mm. That is, thediameter of the inner louver 123 at the central part of the platethickness of the cylindrical wall is 280 mm.

In this way, the inner diameter of the outer louver 121 is greater thanthe outer diameter of the inner louver 123. Thus, the inner louver 123is located inward of the outer louver 121 on the upper surface of thelouver stage 22 as illustrated in FIG. 19. The outer louver 121 and theinner louver 123 have the same height of, for example, 15 to 25 mm (inthe present embodiment, 23 mm).

With the inner louver 123 located inward of the outer louver 121, acylindrical clearance is created between the inner wall surface of theouter louver 121 and the outer wall surface of the inner louver 123. Theouter diameter of the cylindrical clearance (i.e., the inner diameter ofthe outer louver 121) is 317 mm, and the inner diameter of the clearance(i.e., the outer diameter of the inner louver 123) is 283 mm. That is,the interval of the cylindrical clearance between the inner wall surfaceof the outer louver 121 and the outer wall surface of the inner louver123 is 17 mm, and the diameter from the center of the cylindricalclearance in the radial direction is 300 mm, which is the same as thediameter of the semiconductor wafer W. In other words, the center of theclearance between the inner wall surface of the outer louver 121 and theouter wall surface of the inner louver 123 is located immediately belowthe edge of the semiconductor wafer W held by the holding part 7, andthe clearance opposes the peripheral portion of the semiconductor waferW held by the holding part 7.

The procedure of processing performed on the semiconductor wafer W bythe heat treatment apparatus 1 a of the eighth preferred embodiment isthe same as the procedure of the first preferred embodiment. In theeighth preferred embodiment, the opaque cylindrical outer and innerlouvers 121 and 123 are provided between the halogen heating part 4 andthe chamber 6 to control the optical path of light travelling from thehalogen heating part 4 toward the semiconductor wafer W held by theholding part 7. FIG. 20 illustrates how the optical path is controlledby the outer louver 121 and the inner louver 123.

The outer louver 121 and the inner louver 123 are concentrically locatedon the louver stage 22 in a plan view, and the inner diameter of theouter louver 121 is greater than the outer diameter of the inner louver123. Thus, a cylindrical clearance is present between the inner wallsurface of the outer louver 121 and the outer wall surface of the innerlouver 123 as illustrated in FIG. 20. As descried above, in the eighthpreferred embodiment, the cylindrical clearance has an outer diameter of317 mm, an inner diameter of 283 mm, and a height of 23 mm. The intervalbetween the inner wall surface of the outer louver 121 and the outerwall surface of the inner louver 123 is 17 mm.

The cylindrical clearance between the inner wall surface of the outerlouver 121 and the outer wall surface of the inner louver 123 is alsolocated immediately below the peripheral portion of the semiconductorwafer W held by the holding part 7 in the chamber 6 and opposes theperipheral portion. Thus, light emitted from the halogen lamps HL of thehalogen heating part 4 and entering the cylindrical clearance betweenthe inner wall surface of the outer louver 121 and the outer wallsurface of the inner louver 123 is repeatedly reflected by the innerwall surface of the outer louver 121 and the outer wall surface of theinner louver 123, which increases the upward directivity of the light,and reaches the peripheral portion of the semiconductor wafer W held bythe holding part 7 as illustrated in FIG. 20. As a result, the intensityof illumination of the peripheral portion of the semiconductor wafer Wbecomes relatively higher than the intensity of illumination of theinner region of the semiconductor wafer W, and thereby the peripheralportion where a temperature drop is likely to occur is strongly heatedwith the halogen lamps HL during preheating.

It has also been found out that simply installing only a single louverabove the halogen heating part 4 may, on the contrary, increase thetemperature of the region of the semiconductor wafer W that is locatedslightly inward of the peripheral portion during heating with the lightemitted from the halogen lamps HL. If a cylindrical clearance is formedby the outer louver 121 and the inner louver 123 as in the eighthpreferred embodiment, the directivity of the light entering theclearance and travelling toward the peripheral portion of thesemiconductor wafer W is increased. This reduces the possibility thatthe above light will reach the region located slightly inward of theperipheral portion and thereby prevents the region of the semiconductorwafer W located slightly inward of the peripheral portion from beingstrongly heated.

In this way, the cylindrical clearance between the outer louver 121 andthe inner louver 123 increases the directivity of the light emitted fromthe halogen lamps HL and travelling toward the peripheral portion of thesemiconductor wafer W and relatively increases the intensity ofillumination of the peripheral portion. As a result, the peripheralportion of the semiconductor wafer W where a temperature drop is likelyto occur is strongly heated. This configuration effectively resolvesunevenness of the temperature distribution in the surface of thesemiconductor wafer W during preheating.

The combination of the outer louver 121 and the inner louver 123increases the directivity of the light travelling from the halogenheating part 4 toward the peripheral portion of the semiconductor waferW and makes uniform the temperature distribution in the surface of thesemiconductor wafer W at the preheating stage. It is thus also possibleto make uniform the temperature distribution in the surface of thesemiconductor wafer W during flash light irradiation.

In the eighth preferred embodiment, the opaque cylindrical outer andinner louvers 121 and 123 are provided between the halogen heating part4 and the chamber 6 to increase the directivity of the light travellingfrom the halogen heating part 4 toward the peripheral portion of thesemiconductor wafer W held by the holding part 7. During preheating bythe halogen heating part 4, the temperature of the peripheral portion ofthe semiconductor wafer tends to be lower than the temperature of thecentral portion, but it is possible to make uniform the temperaturedistribution in the surface of the semiconductor wafer W duringpreheating by increasing the directivity of the light travelling towardthe peripheral portion and thereby relatively increasing the intensityof illumination. This consequently allows the temperature distributionin the surface of the semiconductor wafer W to be uniform during flashheating.

VARIATIONS

While the above has been a description of preferred embodiments of thepresent invention, various modifications other than the examplesdescribed above are possible without departing from the scope of theinvention. For example, while the light-shielding members 25, 125, 225,and 325 of the above-described preferred embodiments are made of opaquequartz with a large number of superfine air bubbles contained in quartzglass, the material for the light-shielding members 25, 125, 225, and325 is not limited to opaque quartz. For example, the light-shieldingmembers 25, 125, 225, and 325 may be made of a material such as ceramicor metal that is impervious to the light emitted from the halogen lampsHL of the halogen heating part 4. The light-shielding members 25, 125,225, and 325 do not necessarily have to be made of a completely opaquematerial (with 0% transmittance), and may be made of a material having15% or less transmittance of the light emitted from the halogen lampsHL. It is of course preferable for the light-shielding member 25 to bemade of opaque quartz that has no concern about pollution when thelight-shielding member 25 is located within the chamber 6 as in thefifth preferred embodiment.

The louver 21 and the light-shielding members 25, 125, 225, and 325 maybe made of different materials as long as those materials are imperviousto the light emitted from the halogen lamps HL. In the third preferredembodiment, the light-shielding ring 221 and the light-shielding pieces222 may be made of different materials. In this case, thelight-shielding pieces 222 may have different transmittances of thelight emitted from the halogen lamps HL. In the case where overheatregions appearing in the surface of the semiconductor wafer W havevarying temperatures when preheating is conducted with installation ofonly the louver 21, it is preferable for the light-shielding pieces 222to have different transmittance values depending on the temperatures inthe overheat regions. More specifically, a light-shielding piece 222that corresponds to an overheat region having a much higher temperaturethan the other region preferably has low transmittance (as close as 0%transmittance), whereas a light-shielding piece 222 that corresponds toan overheat region having a slightly higher temperature than the otherregion preferably has high transmittance. This configuration allows theintensity of illumination of the overheat regions to be controlled withhigher accuracy and allows the temperature distribution in the surfaceof the semiconductor wafer W to be effectively uniform. In the thirdpreferred embodiment, the light-shielding ring 221 and thelight-shielding pieces 222 may of course have different transmittances.

Similarly, in the fourth preferred embodiment, the light-shielding frame321 and the light-shielding piece 322 may be made of differentmaterials. In this case, the light-shielding frame 321 and thelight-shielding piece 322 may have different transmittances of the lightemitted from the halogen lamps HL.

In the first to fourth preferred embodiments, the shape of thelight-shielding member and the number of parts of the light-shieldingmember are not limited to the examples described above. For example, thelight-shielding member may have, for example, an ellipsoidal shape, astar shape, or a polygonal shape other than the circular shape. Whilethe number of parts of the light-shielding member is one in the firstand second preferred embodiments and more than one in the third andfourth preferred embodiments, the light-shielding member may include anappropriate number of parts depending on the number of overheat regionsthat appear in the surface of the semiconductor wafer W when preheatingis conducted with installation of only the louver 21. When thelight-shielding member includes multiples parts, these parts of thelight-shielding member may be arranged symmetrically or asymmetricallydepending on the distribution of overheat regions in the surface of thesemiconductor wafer W.

In short, in the first to fourth preferred embodiments, thelight-shielding member may be provided in correspondence with overheatregions that have higher temperatures than the other region and appearin the surface of the semiconductor wafer W when preheating with thelight emitted from the halogen heating part 4 is conducted withinstallation of only the louver 21. At this time, the number of parts ofthe light-shielding member, the shape of each part, and thetransmittance of each part are preferably set in accordance with theform (number, shape, temperature) of appearance of overheat regions inthe surface of the semiconductor wafer W.

In the first to fourth preferred embodiments, the height position atwhich the light-shielding member is located is not limited to a positionon the upper surface of the ring stage 24 provided on the upper end ofthe louver 21, and may be a position between the halogen heating part 4and the holding part 7 in the chamber 6. The distance from the halogenheating part 4 to the light-shielding member and the distance from thelight-shielding member to the holding part 7 may preferably be within 20cm.

In the fifth to seventh preferred embodiments, the shape of thelight-shielding member 25 is not limited to an annular shape, and theouter periphery of the light-shielding member 25 may form a polygonalshape or an ellipsoidal shape. Even in this case, the light-shieldingmember 25 is an annular flat plate-like member. The outer dimensions ofthe annular light-shielding member 25 are smaller than the innerdimensions of the louver 21. Even with this light-shielding member 25, aclearance that allows the light emitted from the halogen lamps HL totransmit is created between the inner wall surface of the louver 21 andthe outer periphery of the light-shielding member 25 as long as theouter dimensions of the light-shielding member 25 are smaller than theinner dimensions of the louver 21. Thus, similar effects to the effectsof the fifth to seventh preferred embodiments are achieved.

While in the eighth preferred embodiment, the outer louver 121 and theinner louver 123 are made of opaque quartz with a large number ofsuperfine air bubbles contained in quartz glass, the materials for theouter louver 121 and the inner louver 123 are not limited to opaquequartz. For example, the outer louver 121 and the inner louver 123 onlyneed to be made of a material such as ceramic or metal that isimpervious to the light emitted from the halogen lamps HL of the halogenheating part 4. When the outer louver 121 and the inner louver 123 aremade of metal, stainless steel or aluminum is usable.

When the outer louver 121 and the inner louver 123 are made of a metalmaterial, the inner wall surface of the outer louver 121 and the outerwall surface of the inner louver 123 may be mirror-polished. When theinner wall surface of the outer louver 121 and the outer wall surface ofthe inner louver 123 are mirror-finished surfaces, the reflectivities ofthe surfaces increase, and the light entering the cylindrical clearancebetween the inner wall surface of the outer louver 121 and the outerwall surface of the inner louver 123 is more effectively reflected andthereby has improved directivity.

While in the eighth preferred embodiment, the interval between the innerwall surface of the outer louver 121 and the outer wall surface of theinner louver 123 is 17 mm, the present invention is not limited to thisexample, and this interval may be greater than or equal to 10 mm andless than or equal to 30 mm. If the interval between the inner wallsurface of the outer louver 121 and the outer wall surface of the innerlouver 123 is less than 10 mm, the amount itself of the light enteringthe clearance between the outer louver 121 and the inner louver 123decreases, and it is impossible, even by increasing the directivity oflight, to sufficiently increase the intensity of illumination of theperipheral portion of the semiconductor wafer W. On the other hand, ifthe interval between the inner wall surface of the outer louver 121 andthe outer wall surface of the inner louver 123 exceeds 30 mm, thisincreases the amount of light travelling toward the region of thesemiconductor wafer W, which is located slightly inward of theperipheral portion, during heating with the light emitted from thehalogen lamps HL and relatively increases the intensity of illuminationof that region. In this case, uniformity of the temperature distributionmay, on the contrary, be degraded. Thus, the interval between the innerwall surface of the outer louver 121 and the outer wall surface of theinner louver 123 is set to be greater than or equal to 10 mm and lessthan or equal to 30 mm.

While the two louvers, namely the outer louver 121 and the inner louver123, are provided in the eighth preferred embodiment, the presentinvention is not limited to this example, and the number of louvers maybe three or more. Such three or more louvers are all cylindrical membersmade of a material (e.g., opaque quartz) that is impervious to the lightemitted from the halogen lamps HL. The three or more louvers areinstalled between the halogen heating part 4 and the holding part 7,specifically, on the upper surface of the louver stage 22 as in theeighth preferred embodiment.

The three or more louvers are installed such that their central axespass through the center of the semiconductor wafer W held by the holdingpart 7, i.e., the louvers are concentrically arranged in a plan view.The louvers have different diameters and are sequentially arranged fromoutside to inside in descending order of their outer diameters. Also,the louvers have the same height. When three or more louvers areinstalled, there is a plurality of cylindrical clearances between thelouvers. Thus, in the case where a region for which the intensity ofillumination needs to be relatively increased by increasing thedirectivity of light emitted from the halogen heating part 4 is presentin areas other than the peripheral portion of the semiconductor wafer W,three or more louvers are preferably provided to increase theintensities of illumination of a plurality of regions.

While in the above-described preferred embodiments, the flash heatingpart 5 includes 30 flash lamps FL, the present invention is not limitedto this example, and the flash heating part 5 may include an arbitrarynumber of flash lamps FL. The flash lamps FL are not limited to xenonflash lamps, and may be krypton flash lamps. The number of halogen lampsHL included in the halogen heating part 4 is also not limited to 40, andthe halogen heating part 4 may include an arbitrary number of halogenlamps HL as long as each of the upper and lower rows includes the arrayof a plurality of halogen lamps.

Also, substrates to be processed by the heat treatment apparatus of thepresent invention are not limited to semiconductor wafers, and may beglass substrates for use in a flat panel display such as a liquidcrystal display device, or substrates for solar cells. The technique ofthe present invention is also applicable to other applications such asheat treatment of a high dielectric gate insulating film (high-k film),bonding of metal and silicon, and crystallization of polysilicon.

The application of the heat treatment technique of the present inventionis not limited to flash lamp annealing apparatuses, and the technique isalso applicable to other apparatuses such as a sheet-fed lamp annealingapparatus using halogen lamps, or apparatuses such as a CVD apparatusthat use a heat source other than flash lamps. In particular, thetechnique of the present invention is preferably applicable to abackside annealing apparatus in which halogen lamps are located below achamber and heat treatment is conducted with the light emitted from therear surface of the semiconductor wafer.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore to be understood that numerousmodifications and variations can be devised without departing from thescope of the invention.

What is claimed is:
 1. A heat treatment apparatus for heating adisk-shaped substrate by irradiating the substrate with light,comprising: a chamber that houses a substrate; a holding part that holdsa substrate in said chamber; a light irradiation part in which aplurality of rod-shaped lamps are arranged in a region that is greaterthan a major surface of the substrate held by said holding part and thatopposes the major surface; a cylindrical first light-shielding memberthat is provided between said light irradiation part and said holdingpart, with a central axis of said first light-shielding member passingthrough a center of said substrate, and that is impervious to the lightemitted from said light irradiation part; and a flat-plate annularsecond light-shielding member that is provided between said lightirradiation part and said holding part, with a central axis of saidsecond light-shielding member passing through the center of saidsubstrate, and that is impervious to the light emitted from said lightirradiation part, said second light-shielding member having outerdimensions smaller than inner dimensions of said first light-shieldingmember.
 2. The heat treatment apparatus according to claim 1, whereinsaid second light-shielding member has an annular shape, and said secondlight-shielding member has an outer diameter smaller than an innerdiameter of said first light-shielding member.
 3. The heat treatmentapparatus according to claim 1, wherein said second light-shieldingmember is located on a quartz plate provided on said firstlight-shielding member.
 4. The heat treatment apparatus according toclaim 1, wherein said second light-shielding member is located on aquartz window of said chamber that opposes said light irradiation part.5. The heat treatment apparatus according to claim 1, wherein saidsecond light-shielding member is located inward of said firstlight-shielding member on a quartz stage on which said firstlight-shielding member is located.
 6. The heat treatment apparatusaccording to claim 3, further comprising: a cylindrical thirdlight-shielding member that is provided on said quartz plate, has thesame outer and inner diameters as the outer and inner diameters of saidfirst light-shielding member, and is impervious to the light emittedfrom said light irradiation part.
 7. A heat treatment apparatus forheating a disk-shaped substrate by irradiating the substrate with light,comprising: a chamber that houses a substrate; a holding part that holdsa substrate in said chamber; a light irradiation part in which aplurality of rod-shaped lamps are arranged in a region that is greaterthan a major surface of the substrate held by said holding part and thatopposes the major surface; a cylindrical first louver that is providedbetween said light irradiation part and said holding part, with acentral axis of said first louver passing through a center of saidsubstrate, and that is impervious to the light emitted from said lightirradiation part; and a cylindrical second louver that is providedbetween said light irradiation part and said holding part, with acentral axis of said second louver passing through the center of saidsubstrate, and that is impervious to the light emitted from said lightirradiation part, wherein said first louver and said second louver havethe same height, said first louver has an inner diameter greater than anouter diameter of said second louver, and said second louver is locatedinward of said first louver.
 8. The heat treatment apparatus accordingto claim 7, wherein said first louver and said second louver are locatedwith a clearance between an inner wall surface of said first louver andan outer wall surface of said second louver, said clearance opposing aperipheral portion of said substrate.
 9. The heat treatment apparatusaccording to claim 8, wherein the clearance between the inner wallsurface of said first louver and the outer wall surface of said secondlouver is greater than or equal to 10 mm and less than or equal to 30mm.
 10. The heat treatment apparatus according to claim 7, wherein saidfirst louver and said second louver are made of metal, and the innerwall surface of said first louver and the outer wall surface of saidsecond louver are mirror-finished.
 11. The heat treatment apparatusaccording to claim 7, wherein said first louver and said second louverare installed outside said chamber.
 12. A heat treatment apparatus forheating a disk-shaped substrate by irradiating the substrate with light,comprising: a chamber that houses a substrate; a holding part that holdsa substrate in said chamber; a light irradiation part in which aplurality of rod-shaped lamps are arranged in a region that is greaterthan a major surface of the substrate held by said holding part and thatopposes the major surface; and a plurality of cylindrical louvers thatare located between said light irradiation part and said holding part,with central axes of said louvers passing through a center of saidsubstrate, and that is impervious to the light emitted from said lightirradiation part, said plurality of louvers having the same height andbeing sequentially arranged from outside to inside in descending orderof outer diameters of said plurality of louvers.